Method and device for the machine assembling of crystal diodes



April 20, 1965 w. F. SMITS 3,178,796

METHOD AND DEVICE R THE MACHINE ASSEMBLING 0F C TAL DIODES 4Sheets-Sheet 1 Filed May 12, 1960 INVENTOR WILLEM F. SMITS AGENT A ril20, 1965 F, SW5

METHOD AND DEVICE FOR THE MACHINE ASSEMBLING OF CRYSTAL DIODES 4Sheets-Sheet 2 Filed May 12, 1960 INVENTOR. WILLEM F. SMITS FIG. 2

AG NT April 20., 1965 w. F. SMl-Ts METHOD AND DEVICE FOR THE MACHINEASSEMBLING OF CRYSTAL DIODES 4 Sheets-Sheet 3 Filed May 12, 1960INVENTOR WILLEM F. SMITS April 20, 1965 w. F. SMITS METHOD AND DEVICEFOR THE MACHINE ASSEMBLING OF CRYSTAL DIODES 4 Sheets-Sheet 4 Filed May12, 1960 O D O 0 O O 0 O O O o O O o O O O O 0 O D O O 0 FIG.6

INVENTOR WILLEM F. SMITS AGENT United States Patent C) M 4 Claims. (ill.29-453 This invention relates to the machine assembling of crystaldiodes. Diodes of this kind are known. In a known method formanufacturing diodes substantially by hand, use is made of rods or wireseach with a whisker attached thereto and rods or wires each partlysurrounded by a bulb and sealed thereto, the latter being provided atone of their ends with a flat disc carrying a crystal of, for example,germanium. Such wires will be referred to hereinafter as the anode wiresand the cathode wires. In order to form the said component parts into acrystal diode, in a known method which is usually carried out by hand,the cathode wire together with crystal and bulb is fixedly arranged in aholder centering this part and the anode wire with whisker is fixedlyclamped in a holder slidable in the direction of the length of thiswire, the arrangement being such that the said crystal is in alignmentwith the anode wire. The holder with its anode wire is then moveddownwards, for example by manually screwing down, so that the point ofthe whisker comes to bear on the surface of the crystal. After the pointof the whisker has contacted the surface of the crystal, it is as itwere pricked into this surface by carefully screwing on further theanode holder. Subsequently, the portion of the bulb which is still openis sealed to the anode Wire. After the anode has been assembled, itselectrical properties are tested. This method of assembling crystaldiodes is time-consuming and the ultimate result is highly dependentupon the person carrying out the work, which is not beneficial to theloss percentage and the constancy thereof.

An object of the present invention is to provide a method and a devicewhich permit of assembling large quantities of crystal diodes per hourwith a very high and constant output, and this substantiallyindependently of the person carrying out the work.

In the method according to the invention, this is achieved in that awire slidable in the direction of its length and provided with a whiskeris brought in an adjusting head opposite a crystal of a cathode fixedlyarranged in the longuitudinal direction thereof, whereupon the whiskerend of this wire is moved in the direction of its length towards thecrystal and brought into contact with it so that the end of the whiskercomes to bear on the crystal with a substantially constant andadjustable force. During this contact, the electrical properties overthe contact area may be tested. If the measurement yields favourableresults, the whisker wire is sealed to the glass bulb of the cathodewhile maintaining its position with respect to the crystal.

In another important embodiment of the method according to theinvention, if the result of the measurement as to electrical propertiesis unfavourable, the anode wire with its whisker is removed from thecrystal and slightly turned about its longitudinal axis and then againmoved towards the crystal, whereupon another measurement may be carriedout. By repeating this process several times, it may be ensured that thesealing operation takes place only when the measurement as to givenelectrical properties yields favourable results. It has been found thatthe finished product need not be tested afterwards with regard toelectrical properties. As a rule, two times prick- 3,178,795 PatentedApr. 20, 1965 ing usually suffices, but the said method may be beextended, if necessary, for a third pricking operation.

A device according to the invention is of the turret type or the likehaving an adjusting zone, a sealing zone and a cooling zone, sealingheads being grouped at its circumference on the same pitch circle, eachcomprising a pair of tongs for holding the cathode portion with crystalin position, a holder for the directed and magnetic holding of a wirewith whisker (anode portion) so that the crystal of the cathode portionis aligned with this wire, a device for controlled displacement of thewhisker wire in the direction of its length, during which the movementis guided so that, at the end thereof, the point of the whisker comes tobear on the crystal with a force substantially constant and adjustablefor each adjusting head, a device displaceable around the whisker wirein the direction of length thereof for heating the cathode and anodebrought together, and abutments for receiving and giving severalcommands, while there are also means for testing the electricalproperties of the contact between the crystal and the point of thewhisker bearing thereon, before the heating device is made operative. Itis possible to position the adjusting heads, instead of in a circle,into, for example, a straight line, one after another, but the turretshape is preferred for practical reasons.

The above-mentioned device is preferably designed so that it can becoupled to transport tracks on which standard holders can be conveyed.These holders are such that they can contain component partsmanufactured at another area, while these component parts can beautomatically taken out of the holders and placed in the machine andhence without contact by hand, the final product manufactured on themachine being replaced in a similar manner in the holders on thetransport track.

The method and the device according to the invention permit ofassembling large quantities of crystal diodes per unit-time with ahighly divergent number of types.

In order that the invention may be readily carried into effect, oneembodiment thereof will now be described in detail, by way of example,with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 shows a diagram of the method according to the invention;

FIGURE 2 shows an adjusting head provided with some detail drawings 2ato 2 FIGURE 3 shows a device for obtaining a constant pressure betweenthe whisker and the crystal;

FIGURE 4 shows diagrammatically in what manner the anode wire slidablein a holder can be slightly turned in this holder;

FIGURE 5 is a diagrammatic view of a turret type machine equipped withadjusting heads;

FIG. 6 shows a top plan, side elevation and sectional, and frontelevation and sectional view of the details of the transport holders.

In the method according to the invention, an anode wire 1 provided witha whisker 3 (FIGURE 1a) is slidably arranged in a holder 6 (FIGURE 1b),while a cathode wire 2 provided with a crystal 4 and sealed to a glassbulb or housing 5 is held in position through its bulb portion in asupporting member 7. Subsequently, the anode wire is displaced in thedirection of its length (FIGURE 1c) until its whisker end comes to bearon the upper side of the crystal 4 with a force P. In this position, theelectrical properties may be tested over the contact area between thewhisker and the crystal. If the measurement yields favourable results,that side of the bulb sealed to the cathode wire which is still open isnow sealed to the anode wire by means of a heating device whilemaintaining the force P (FIGURE 1f), whereupon the finished product(FIGURE 1g), after cooling, can be removed as a crystal diode from theholders 6 and 7.

If the result of the measurement should be unsatisfactory, thenaccording tothe invention, before the sealing operation takes place, thewhisker Wire is removed from the crystal and this wire is given a smallangular displacement (FIGURE 1d), whereupon the anode wire with whiskeris again brought onto the crystal (FIGURE 1e). Then a similarmeasurement may be carried out as described with FIGURE 10. If themeasurement still does not yield satisfactory results, the removal ofthe whisker from the crystal and the slight angular displacement of theanode wire may be repeated, if desired. There can thus be pricked andmeasured several times before the anode wire is sealed to the bulb.

In order to obtain the desired adjustable and preferably constantcontact pressure between the whisker and the crystal, it is necessaryfor, the anode wire, after its whisker end has come into contact withthe surface of the crystal, to be lowered over a small further distance.For' this purpose, the invention utilizes a device which will bedescribed more fully hereinafter.

The operations above described may be carried out by means of anadjusting head, the structure of which, may be seen from FIGURE 2showing a detailed drawing and FIGURES 2a to 2]. The following parts canbe distinguished in this adjusting head: a holder 6 provided withwedge-shaped location places and a magnetic block 12 for the directedand slidable holding of an anode wire 1 in the direction of' its length,which holder is rigidly connected via bodies 10 and 11 to a frame 8 ofthe adjusting head, a pair of tongs 7 for the centered supporting, of atubular glass bulb sealed toone end of a cathode wire provided with acrystal, a pin 13 being present for receiving commands for opening andclosing the tongs, (FIGURES 2a and 2b), a slidable rod 16 having anextremity17 for displacing the anode wire 1 with its whisker in thedirection of its length, whichrod can perform a vertical movement bymeans of a lever 20 pivoted on a shaft 21 and, during this movement, isguided in a bearing 25 (FIGURE 2e), a heating device 14 slidable in thedirection. of its length around the glass bulb 5 and connected to bodies26 and 29 of insulating material, which heating device can turn about ashaft 24 and canbe connected by means of pins 28 (in a manner notshown)to an energizing source, (FIGURES 2 and 2e). Forming part oftheadjusting head is also a rod having carriers 22 and 23 connectedthereto, which rod can move in the direction of its length. by means ofa cam (not shown). During the upward movement of the rod 15, thecarriers 22 and 23 cause-theextremity 17 of 'rod 16 and the heatingdevice 14 to be moved upwards with a stroke de termined by abutments,the adjustment being such that at first the lever and the rod 16. andthen the heating device are moved upwards. l The operation of thisdevice can be explained as follows.

When the parts 17 and 14 occupy their upper positions,

a cathode isfirst placed in the tongs 7 (FIGURES 2a and 2b). Next, therod 15 is moved downwards so that the heating device 14 surrounds thecathode (FIGURE 20). The rod 15 is maintained in this position for ashort time until an anode wire 1 with whisker is placed in the holder 6.(FIGURE 2d). Subsequently, the rod 15 is moved down further, duringwhich movement the position of device 14 is maintained by means of.spring steel strips 27 (FIGURE 2) and the extremity 17 of the rod16slides theanode wire downwards (FIGURE 2e). 'An abutment 31 and a setbolt 32 are adjusted so that, after the whisker point of the anode wire1 has come into contact with the two contact points 36 and 37 which areconnected through connecting cables 18 and 19 to a measuring device (notshown) for testing the electrical properties of the contact between thewhisker and the crystal. As previously described with the methodaccording to the invention, in the event ofa measurement yieldingunsatisfactory results,

7 the anode wire with its whisker is removed from the crystal. For thispurpose, the extremity 17 of rod 16 is provided with a magnet which canpull up the anode wire 1 in the wedge-shaped carriers of holder 6 uponan upward movement of rod 16. The anode wire can now be 7 given anangular displacement in a manner as shown diagrammatically in FIGURE 4,whereby the flat side of a rubber block 39 which is moved towards theanode wire and connected to a finger 38 is brought against the anodewire in the direction indicated by arrow 40a and, subsequently, thefinger 38 is moved over a short distance in mounted on a table which canrotate in a stepwise manner crystal, the rod 16 can slightly sinkfurther due to itsnat- 1 of rod 16 uponthe point of the whisker of theanode wire 1, in a further embodiment of the invention, the extremityand is turned in each case one position with respect to a frame 41. Withrespect to the frame 41, there can be distinguished in this turret aplurality of zones, namely: an adjusting zone A, a sealing zone B, acooling zone C, and a zone D for the supply of anode wires and cathodewires and the discharge of the diodes ultimately manufactured on theturret.

In the adjusting zone, an anode wire is moved onto a crystal at positionb. The electrical properties of this contact are tested at position 0.The whisker is lifted from the crystal at position d, while upon turningof the turret to the subsequent position the anode wire is slightlyturned by means of a rubber block. Next, the

. anode wire is again brought against the crystal at position e. Thecycle may then be repeated, if desired, at the positions 7, g and h. Inaddition, the frame of the machine is provided at the circumference ofthe turret with members for the electro-magnetic blocking of thedescribed operations at the positions d to k and g to 11' respectively,as soon as a measurement as to electrical properties at position c orposition I yields satisfactory results. If the proper electrical contactbetween the .whisker and, the crystal is still not obtained during thelast measurement at k, the cathode tongs are opened at position mlikewise'electromagnetically by means of a pin 19 ofthe adjusting head(FIGURE 2a) and the bulb with its cathode wire falls out of the tongs.

.In the sealing zone B, the heating device of each ad justing head isenergized, the anode wire being sealed to the bulb of the cathode whilemaintaining the contact pressure between the whisker and the crystalwhich has been establishejdin the adjusting zone.

The sealed diodes are cooled inaquiet ambiance in the zone C. 7

The machine also comprises two guide tracks 42 and 43 for the supply,and discharge oftransport holders 52 of a standard type. These holdershave a plurality of apertures 54 (FIG.-6) for vertically inserting intothem anode wires'with whiskers and cathode wires with bulbs, which wiresare straight in themselves, the holders also having a lateral flankprovided with a number of teeth 56 such that the number of teethcorresponds to the number of apertures. When placed in guide tracks 42and 43, a driving ratchet mechanism 47 can displace the holders in theseguide tracks in a manner such that for each rotation of the turret byone position theholders also move on one tooth. Active in synchronismwith the transport movement of the said holders are take-over membersfor taking the cathode wires and anode wires out of the holders andplacing them in the positions s and t of the machine in accordance withswinging movements 48 and 49 in relation to the transport holders 52 inthe guide tracks 42 and 43, and also for taking diodes and any whiskerwires out of the machine at the positions It and r in accordance withswinging movements 50 and 51 shown in the figure. In conclusion, meansare provided in the zone D for the electromagnetic blocking of thevarious operations in this zone, this blocking being active so that, ifthe member for taking out diodes does not function, the standardtransport receives a command not to insert an anode wire or cathode wireat the position of an adjusting head which still contains a diode. Theblocking is also adjusted so that, if a cathode wire is not placed inthe machine, neither is an anode wire placed in the correspondingadjusting head.

What is claimed is:

1. An apparatus for assembling crystal diodes, each provided with acathode portion and a whisker anode portion, said cathode portion beingprovided with a glass housing, comprising a rotatable turret having anadjusting zone, a sealing zone and a cooling zone, a plurality ofsealing heads being located at the circumference of said turret, each ofsaid sealing heads including a pair of tongs for holding said cathodeportion with its crystal, a holder for said whisker anode portionwhereby the crystal of the cathode portion is aligned with said whisker,a device for controlling displacement of said whisker in the directionof its length whereby the whisker comes to bear on the top surface ofsaid crystal with a force substantially constant and adjustable for eachhead, a heating member displaceable about said whisker and heating saidglass housing, means for testing the electrical properties of thecontact and the point of the whisker bearing thereon prior to theheating member being made operative, a plurality of transport tracksadjacent to said turret, a plurality of holders adapted to be movable onsaid transport tracks and having the cathode portions therein, means fortaking said cathode portions out of said holders and placing them insaid sealing heads, and another means for taking each of said assembledcrystal diodes out of said apparatus and placing them in selectedholders on the transport tracks.

2. An apparatus for assembling crystal diodes as claimed in claim 1wherein said heating member is an electrical heating device comprisingheating coils.

3. An apparatus for assembling crystal diodes as claimed in claim 1further comprising means for removing the whisker from the crystal, anda plurality of members for slightly turning said whisker about itslongitudinal axis, said members only being operative if the measurementof the electric properties of the contact area. and the point of thewhisker bearing is unfavorable.

4. An apparatus for assembling crystal diodes, each provided with acathode portion and a whisker anode portion, said cathode portion beingprovided with a glass housing, comprising a rotatable turret having anadjusting zone, a sealing zone and a cooling zone, a plurality ofsealing heads being located at the circumference of said turret, each ofsaid sealing heads including a pair of tongs for holding said cathodeportion with its crystal, a holder for said whisker anode portionwhereby the crystal of the cathode portion is aligned with said whisker,a device for the controlled displacement of the whisker being providedwith a slidable weight so mounted in said holder as to urge the whiskeragainst the crystal with a force substantially constant and adjustablefor each head, a heating member, means for displacing said heatingmember about said whisker and heating said glass housing, means fortesting the electrical properties of the contact the point of thewhisker bearing thereon prior to the heating member being madeoperative, a plurality of levers with abutments for controlling themovement of said Weight, and a spring and another weight inside saidfirst mentioned movable weight, said other weight being slidable thereinagainst spring pressure, the Whisker end at the lower position of saidfirst mentioned movable weight bearing on the crystal of said cathodeportion with a force substantially determined by said spring.

References Cited by the Examiner UNITED STATES PATENTS 1,833,660 11/31Siebs 219- 2,649,560 8/53 Blair 317236 X 2,693,555 11/54 North et al.2925.3 X 2,697,806 12/54 Gates 2925.3 X 2,757,440 8/56 Carman 2925.32,823,789 2/58 Henning 198-131 2,856,571 10/58 Holzemann 2925.3 X2,984,046 5/61 Brewer 2925.19 3,047,933 8/62 Chick 2925.3

RICHARD H. EANES, JR., Primary Examiner.

THOMAS E. BEALL, LEON PEAR, WHITMORE A.

WILTZ, Examiners.

1. AN APPARATUS FOR ASSEMBLING CRYSTAL DIODES, EACH PROVIDED WITH ACATHODE PORTION AND A WHISKER ANODE PORTION, SAID CATHODE PORTION BEINDPROVIDED WITH A GLASS HOUSING, COMPRISING A ROTATABLE TURRET HAVING AADJUSTING ZONE, A SEALING ZONE AND A COOLING ZONE, A PLURALITY OFSEALING HEADS BEING LOCATED AT THE CIRCUMFERENCE OF SAID TURRET, EACH OFSAID SEALING HEADS INCLUDING A PAIR OF TONGS FOR HOLDING SAID CATHODEPORTION WHICH ITS CRYSTAL, A HOLDER FOR SAID WHISKER ANODE PORTIONWHEREBY THE CRYSTAL OF THE CATHODE PORTION IS ALIGNED WITH SAID WHISKER,A DEVICE FOR CONTROLLING DISPLACEMENT OF SAID WHISKER IN THE DIRECTIONOF ITS LENGTH WHEREBY THE WHISKER COMES TO BEAR ON THE TOP SURFACE OFSAID CRYSTAL WITH A FORCE SUBSTANTIALLY CONSTANT AND ADJUSTABLE FOR EACHHEAD, A HEATING MEMBER DISPLACEABLE ABOUT SAID WHISKER AND HEATING SAIDGLASS HOUSING, MEANS FOR TESTING THE ELECTRICAL PROPERTIES OF THECONTACT AND THE POINT OF THE WHISKER BEARING THEREON PRIOR TO THEHEATING MEMBER BEING MADE OPERATIVE, A PLURALITY OF TRANSPORT TRACKSADJACENT TO SAID TURRET, A PLURALITY OF HOLDERS ADAPTED TO BE MOVABLE ONSAID TRANSPORT TRACKS AND HAVING THE CATHODE PORTIONS THEREIN, MEANS FORTAKING SAID CATHODE PORTION OUT OF SAID HOLDERS AND PLACING THEM IN SAIDSEALING HEADS, AND ANOTHER MEANS FOR TAKING EACH OF SAID ASSEMBLEDCRYSTAL DIODES OUT OF SAID APPARATUS AND PLACING THEM IN SELECTEDHOLDERS ON THE TRANSPORT TRACKS.